Semiconductor devices such as memory devices incorporating three-dimensional structures are generally formed of extremely well defined and repetitive structures applied onto a base wafer. The process of manufacturing the semiconductor devices includes a number of processing steps such as for example lithography, for the fabrication of the structures, patterns, etc. onto the base wafer. In the current scenario, to improve the yields, the designs, patterns, structures have to be reduced to very small sizes of around sub-micron levels. Accordingly, any defect in the process or patterns fabricated may hamper the yield and quality of the semiconductor devices. Therefore, In order to maintain high manufacturing yield and thus low manufacturing costs, these semiconductor devices have to be analyzed for abnormalities and anomalies. The industry roadmap has identified a lack of suitable inspection tools that are able to perform geometrical and compositional analysis of 3D micron and sub-micron scale features. Conventional techniques have shortcomings including less than desirable speed and accuracy. With respect to identifying defects in the manufacturing process, manual classification has been required of anomalies and manual diagnosing of the cause of defects. Such manual inputs may have resulted in inconsistent results and consumption of considerable operator time.
Recently, the focus has been shifted to EDXRF based metrology techniques for analyzing the three dimensional semiconductor devices for abnormalities and anomalies. ED-XRF is a reliable, sensitive and widely used technique for the detection and quantification of elemental concentrations within a sample semiconductor device.
To analyze very small size semiconductor devices, Micro-ED-XRF techniques have been used which are capable of analyzing elemental composition and concentrations for features with lateral resolution in the range of tens of microns down to single digit microns for a wide range of elements as designated in the periodical table. However, these micro-edxrf based techniques and systems are not subtle enough to accurately detect the anomalies, because these techniques are limited to a certain height or depth beyond which secondary emitted radiation is unable to reach the detectors due to obstruction by atomic interactions in their path.
Consequently, the inspection of these semiconductor devices having very small sized structures in range of sub-micron level cannot be done accurately using the EDXRF system alone.
Therefore, there is a need in art for simple and accurate systems that are able to accurately inspect the very small size features of these semiconductor devices.